So skipping the fact that a little cocktail glass can't dent a vehicle without someone actually smashing it intentionally and very hard into the car, you're saying both the upper and lower portions of his arm were cut up by the taillight? How does that work?
How would just his arm cause a taillight to fracture into 45 pieces? Or at all, for that matter? Those things are hard as a *advertiser censored*. Try punching one.
If only his arm was hit, not only would his shoe not have been knocked off, he'd have walked away with maybe a bruise or two at most. He wouldn't have flown anywhere, never mind 30 feet.
The head injury was very serious and incapacitating. Your interpretation ignores this. If fact, this entire scenario is completely fanciful.